Saremba, Scott P2020-04-212020-04-211974-06https://hdl.handle.net/11299/212490A Plan B Paper submitted to the faculty of the Graduate School of the University of Minnesota by Scott P. Saremba as a Requirement for the Degree Master of Science (Plan B), June 1974.Previous work on densities of liquid silicate systems suggest that it is mathematically possible to determine whether phenocrysts in a magma should settle or float based on the density difference between the magma and phenocrysts. The density of most magmatic liquids can be ca1culated from the equation: dmelt = εiXiMi/ViM1, where Xi is the mole fraction of component I, vi its partial molar volume, and Mi its gram formula weight. Mathematically derived results of density difference compare favorably with 4 out of the 5 field observations made on lavas and sills of the North Shore Volcanic Group. The good correlation between the results of the author's mathematically derived results and the field observation support the use of the mathematical model as a meaningful indicator of floating or settling of phenocrysts in a crystallizing melt. The single inconsistency (1 out of 5) suggest that factors other than density difference such as viscosity, affects density, crystal shapes, and convection in magmatic melts may have an effect on the settling or floating of phenocrysts. [See item for proper illustration of mathematical formula]enPlan Bs (project-based master's degrees)Department of Earth and Environmental SciencesUniversity of Minnesota DuluthMaster of ScienceMaster of Science in GeologyScholarly Text or Essay